Thermal physics of the lead chalcogenides PbS, PbSe, and PbTe from first principles

Abstract

The lead chalcogenides represent an important family of functional materials,\nin particular due to the benchmark high-temperature thermoelectric performance\nof PbTe. A number of recent investigations, experimental and theoretical, have\naimed to gather insight into their unique lattice dynamics and electronic\nstructure. However, the majority of first-principles modelling has been\nperformed at fixed temperatures, and there has been no comprehensive and\nsystematic computational study of the effect of temperature on the material\nproperties. We report a comparative lattice-dynamics study of the temperature\ndependence of the properties of PbS, PbSe and PbTe, focussing particularly on\nthose relevant to thermoelectric performance, viz. phonon frequencies, lattice\nthermal conductivity, and electronic band structure. Calculations are performed\nwithin the quasi-harmonic approximation, with the inclusion of phonon-phonon\ninteractions from many-body perturbation theory, which are used to compute\nphonon lifetimes and predict the lattice thermal conductivity. The results are\ncritically compared against experimental data and other calculations, and add\nnew insight to on-going research on the PbX compounds in relation to the\noff-centring of Pb at high temperatures, which is shown to be related to phonon\nsoftening. The agreement with experiment suggests that this method could serve\nas a straightforward, powerful and generally-applicable means of investigating\nthe temperature dependence of material properties from first principles.\n

Keywords

Affiliated Institutions

• Kyoto University JP
• University of Bath GB

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